Red Hat Bugzilla – Bug 984230
Broken aliasing on small font sizes since version 2.00
Last modified: 2015-06-29 20:39:51 EDT
The pixel aliasing of glyphs, especially vertical lines/parts is broken since version 2.00 on Windows (renderer). This applies to all Liberation Font types when ClearType is off, i.e. with gray-scale anti-aliasing only. Version 2.00 has incurred aliasing for all font sizes. Version 2.00.1 fixed this by disabling anti-aliasing for sizes < 14pt. Yet, vertical lines/parts and some transitions from curves to lines are still rendered incorrectly or with artifacts. This may also apply to Fedora GNOME desktops, but it has been observed on Windows first. Although, I am not a font design specialist, I suppose that this problem exists because version 2.00 is based on Google Crosscore fonts and hinting information for small font sizes is missing. This is a show stopper for software rendering Libration Fonts on pixel based digital displays. Software packages like LibréOffice are also negatively affected by this issue (although on displays only). Please resolve this issue or revert verion 2.00 and later to beta status. How to reproduce: Windows XP/2003 Compare Liberation Fonts version 1.07 to version 2.00.1 for small font sizes < 14pt. Windows Vista and later Disable ClearType Compare Liberation Fonts version 1.07 to version 2.00.1 for small font sizes < 14pt. Version 1.07 has been correctly hinted, hence is perfectly pixel aligned.
Thanks for reporting this. How croscore work with respect to this issue? will be good if you can provide some screenshots.
Hi Jacob, will be very helpful if you can provide screenshot
Created attachment 782150 [details] Liberation Mono Regular 1.07.2 Note that all glyphs are properly pixel aligned and hinted.
Created attachment 782153 [details] Liberation Sans Regular 1.07.2 Note that all glyphs are properly pixel aligned and hinted.
Created attachment 782155 [details] Liberation Serif Regular 1.07.2 Note that all glyphs are properly pixel aligned and hinted.
Created attachment 782156 [details] Liberation Mono Regular 2.00.0 Note that small font sizes are rendered with gray-scale anti-aliasing, which is wrong for sizes < 14pt. Vertical strokes are not pixel aligned. This apples for all font sizes (wrong again). It is difficult to see whether hinting is correct, but probably not, because as it seems version 2.00.1 just turns off anti-aliasing for sizes < 14pt (compare to version 2.00.1).
Created attachment 782157 [details] Liberation Sans Regular 2.00.0 Note that small font sizes are rendered with gray-scale anti-aliasing, which is wrong for sizes < 14pt. Vertical strokes are not pixel aligned. This apples for all font sizes (wrong again). It is difficult to see whether hinting is correct, but probably not, because as it seems version 2.00.1 just turns off anti-aliasing for sizes < 14pt (compare to version 2.00.1). Do not get yourself confused by the file's wrong internal version number.
Created attachment 782159 [details] Liberation Serif Regular 2.00.0 Note that small font sizes are rendered with gray-scale anti-aliasing, which is wrong for sizes < 14pt. Vertical strokes are not pixel aligned. This apples for all font sizes (wrong again). It is difficult to see whether hinting is correct, but probably not, because as it seems version 2.00.1 just turns off anti-aliasing for sizes < 14pt (compare to version 2.00.1). Do not get yourself confused by the file's wrong internal version number.
Created attachment 782161 [details] Liberation Mono Regular 2.00.1 Note that anti-aliasing is disabled for font sizes < 14pt, which is correct. Though, hinting is missing. Font sizes >= 14pt are anti-aliased, but vertical strokes or vertical glyph positioning is not pixel aligned (as in version 2.00.0). Do not get yourself confused by the file's wrong internal version number.
Created attachment 782162 [details] Liberation Sans Regular 2.00.1 Note that anti-aliasing is disabled for font sizes < 14pt, which is correct. Though, hinting is missing. Font sizes >= 14pt are anti-aliased, but vertical strokes or vertical glyph positioning is not pixel aligned (as in version 2.00.0). Do not get yourself confused by the file's wrong internal version number.
Created attachment 782167 [details] Liberation Serif Regular 2.00.1 Note that anti-aliasing is disabled for font sizes < 14pt, which is correct. Though, hinting is missing. Font sizes >= 14pt are anti-aliased, but vertical strokes or horizontal glyph positioning is not pixel aligned (as in version 2.00.0). Do not get yourself confused by the file's wrong internal version number.
> Font sizes >= 14pt are anti-aliased, but vertical strokes or vertical glyph > positioning is not pixel aligned (as in version 2.00.0). I meant /horizontal/ glyph positioning, of course.
Rather than Liberation 2.00.1 images you have attached Liberation 1.07.2 images. But its fine i understood the problem. Yes, hinting bytecode is major problem for shifting from Liberation 1.07.2 to Liberation 2.00.0 We need to decide between hinting Vs Glyph coverage. Fixing hinting bytecode of Liberation 2 does not looks feasible to me. But i will see if with some configuration in GASP table if we can improve it bit more. How about Croscore does it gives expected results At small sizes? though i will check this..
(In reply to Pravin Satpute from comment #13) > Rather than Liberation 2.00.1 images you have attached Liberation 1.07.2 > images. But its fine i understood the problem. No, I have attached 1.07.2, 2.00.1, and 2.00.2. Please read the posted comments more carefully. The internal file versioning has not been updated correctly. The point is, that since version 2.00.0 Liberations Fonts are fatally messed up. There are two problems left since version 2.00.2: Hinting and horizontal positioning of glyphs. It may be that horizontal positioning may be actually the only problem, so that when it is done correctly everything else will fall in place. I cannot tell for sure, because I am not a font designer.
Created attachment 782839 [details] Google Croscore Arimo Regular 1.23 > How about Croscore does it gives expected results At small sizes? though i > will check this.. As one can see Google Croscore is no alternative either. Anti-aliasing is on by default for font sizes < 14pt. Horizontal glyph positioning is not correct either.
Created attachment 782840 [details] Google Croscore Cousine Regular 1.20 > How about Croscore does it gives expected results At small sizes? though i > will check this.. As one can see Google Croscore is no alternative either. Anti-aliasing is on by default for font sizes < 14pt. Horizontal glyph positioning is not correct either.
Created attachment 782841 [details] Google Croscore Tinos Regular 1.23 > How about Croscore does it gives expected results At small sizes? though i > will check this.. As one can see Google Croscore is no alternative either. Anti-aliasing is on by default for font sizes < 14pt. Horizontal glyph positioning is not correct either.
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(In reply to Fedora End Of Life from comment #18) > Package Maintainer: If you wish for this bug to remain open because you > plan to fix it in a currently maintained version, simply change the > 'version' to a later Fedora version prior to Fedora 18's end of life. Thank you for not letting this bug slide. Anyway, are the any news to report on what kind of action and when it is going to be taken to fix this problem?
Due to hinting incompatibility we shifted back to liberation 1.07 in Fedora. In long term we need to improve hinting instructions of Liberation 2 and as said earlier that is big task. Presently not sure when this will happen.
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Fedora 20 changed to end-of-life (EOL) status on 2015-06-23. Fedora 20 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. If you are unable to reopen this bug, please file a new report against the current release. If you experience problems, please add a comment to this bug. Thank you for reporting this bug and we are sorry it could not be fixed.